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Variation in activation time during bipolar vs extended bipolar left ventricular pacing

Research output: Contribution to journalArticlepeer-review

Original languageEnglish
JournalJournal of Cardiovascular Electrophysiology
Early online date14 Aug 2018
Accepted/In press31 Aug 0007
E-pub ahead of print14 Aug 2018


King's Authors


BACKGROUND: Cardiac resynchronisation therapy (CRT) is typically delivered via quadripolar leads that allow stimulation using either true bipolar pacing, where stimulation occurs between two electrodes (BP) on the quadripolar lead or extended bipole (EBP) LV pacing, with the quadripolar electrodes and RV coil acting as the cathode and anode respectively. True bipolar pacing is associated with reductions in mortality and it has been postulated that these differences are the result of enhanced electrical activation.

METHODS: Patients undergoing a CRT underwent an electrocardiographic imaging (ECGI) study where electrical activation data was recorded whilst different LV pacing vectors were temporarily programmed.

RESULTS: There were no differences in the total electrical activation times or dispersion of electrical activation between biventricular pacing with bipolar or corresponding EBP LV vector configurations (LVtat BP 74.70 ± 18.07 vs EBP 72.4 ± 22.64; P=0.45.) When dichotomised according to aetiology, no difference was observed in the activation time with either BP or EBP pacing (LVtat BP ICM 72.2 ± 17.4 vs BP DCM 79.9 ± 18.9; P=0.38.).

CONCLUSIONS: Bipolar pacing alters the mechanical activation sequence of the LV and is associated with reductions in all-cause mortality. It has been postulated these benefits derive from improvements in electromechanical activation of the LV. Our study would suggest that true bipolar pacing does not necessarily result in more favourable activation of the LV or improved electrical resynchronisation and other mechanisms should be explored.

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